The long-term objective of the proposed study is to develop a new medium for optimal preservation of human donor corneas. Specfic aims are as follows: 1) Investigation of condtions that provide corneas with sufficient energy and maximum protein synthesis while lactic acid accumulation is eliminated or substantially reduced; 2) Formulation of a new medium for optimal corneal storage; 3) Tests on efficacy of augmented corneal strorage medium. At present, penetrating keratoplasty for restoring sight in patients with corneal opacity has been highly successful. However, because of the short supply of surgical-quality donor conrneas, many patients in the United States, who now wait up to a year for available donor tissue, suffer unnecessary blindness. The McCarey-Kaufman medium has been credited for its effectiveness in preserving donor corneas up to 96 hours. This study is to establish a biochemical basis for the development of a medium which may extend the preservation of donor corneas beyond the current upper limit. This, in turn, will provide surgeons with flexibility in performing operations, improves scheduling of elective surgery, and permits more cost-efficient use of operating rooms. In addition, patients will benefit from the enhanced physiological quality of donor tissue which is high priority. A medium, with which isolated corneas may maintain optimal metabolic functions for an extended storage period, will be developed by systematic biochemical studies. These include a total amino acid analysis to establish optimal concentrations of amion acids for isolated corneas and metabolic studies to evaluate the potential of ketone bodies and other substrates as an alternative energy source for stored corneas. Efficacy of augmented medium for optimal corneal storage will be evaluated on the basis of glycolytic and respiratory activity, intactness of endothelium, and weight and thickness of the corneas after storage.